1. Field of the Invention
The present invention relates to a delivery station of a converting press for paper or cardboard sheets including a transverse roller located downstream from the delivery area and a movable carriage downstream from the aforesaid roller, which is able to receive a plurality of bars so as to form a non-stop blanking delivery rack, the aforesaid carriage being guided in a longitudinal direction by a carrying device. The words xe2x80x9cupstreamxe2x80x9d,xe2x80x9cdownstreamxe2x80x9d,xe2x80x9clongitudinalxe2x80x9d and xe2x80x9ctransversexe2x80x9d are used here with reference to the running direction of the sheets in the press.
2. Related Art
In delivery stations as previously defined, the blanking operation is performed at an upstream blanking station, and involves, after converting and complete waste stripping, breaking the nicks between the sheet blanks by means of an upper male tool and a lower female tool vertically assembled one above the other in the sheets delivery area. The upper tool is made of pushing devices slightly smaller than the circumference of the blanks. The lower tool is made of longitudinal and transverse bars forming a rack corresponding to the circumference of the blanks. The blanks fall through the spaces of this rack and pile up vertically in,the delivery area.
To form piles of separate and fixed blanks under these tools, on the delivery vane of the delivery station, a periodic insertion of a stabilization sheet is needed. So that this insertion can be carried out without stopping production, one uses a device called a non-stop delivery rack. This device includes a carriage movable in the longitudinal direction of the press. The carriage comprises two transverse beams on which bars can be laid out longitudinally to form a non-stop blank delivery rack. The bars are, generally rod-shaped. The head of each rod can fit into an opening of the carriage beam which is furthest away from the delivery station and can be secured to it by screwing. The end of the rod nearest the head rest, on the second transverse beam of the carriage. The opposite end of the rod rests on a transverse roller located just next to and downstream from the blanks delivery station. To carry on an insertion operation, the movable carriage moves the bars under the lower blanking tool and a pair of bars come to support each blank falling down. For large size blanks, a larger number of bars per blank can be used. The non-stop delivery rack receives from time to time the blanks piling up during the insertion operations. After each insertion operation, the bars forming the rack leave the delivery area, by a longitudinal movement of the movable carriage, crossing with vertical joggers of the lower blanking tool, so as to lay the blanks onto the insertion sheet.
A preselector determines the number of cuttings for each inserted package as well as the number of packages and/or the height of the piles. The whole device functions automatically and goes on according to a previously set operating time.
A disadvantage of this non-stop delivery rack device occurs in the fact that the height of the temporary storage on the bars engaged in the delivery area is only of about 35 mm. However, an insertion period is of approximately 20 to 30 seconds. The storage height is sufficient for cardboard sheets of low thickness or low basis weight and for relatively slow processing speeds. For the uptodate fastest production rates, as well as for relatively thick cardboard or waste board sheets, this storage height. becomes insufficient. If the thickness of a new thin cardboard sheet is of about {fraction (3/10 )} of millimeters, this thickness increases up to {fraction (5/10)}, even more, when it is driven back to carry out the folds of the board. With a production rate of 3 sheets per second, the available height of storage of 35 mm can be reached in approximately 20 seconds"" time, even less. To increase the time available for insertion, is has been proposed to increase this storage height while lowering the level of the non-stop rack. But in this case, the precision of the laying out of the blanks is reduced, particularly in the case of small-size blanks. With a width lower than 10 cm and with a double waste height, the blanks fall crosswise and the piles are badly piled up.
The aim of this invention is to increase the storage capacity on the nonstop delivery rack, while maintaining the height of the blanks waste at the lowest level so as to ensure a good piling up.
This aim is reached in a previously defined delivery station by the fact that the station comprises an elevating device that simultaneously moves the roller and the movable carriage downwards while the blanks are piling up on the delivery rack.
By use of the elevating device according to the invention, the delivery rack laid onto the movable carriage and on the roller moves downward while the blanks are piling up on this rack during the insertion operation. The insertion period is thus obviously increased. The height of the blanks waste thus becomes adjustable, and the height of the free waste can stay at lower-level, which is particularly advantageous for low blanks.
According to a procedure of the invention, the vertical displacement downwards is preset owing to the work carried out by the press, particularly according to the thickness of the board dealed with.
According to another procedure, the vertical displacement downwards is controlled by the detection of the upper sheet of the pile laying onto the delivery rack.
The carrying device of the movable carriage and the transverse roller can be rigidly secured in a vertically movable frame. The vertically movable frame can especially be a frame crossing the whole width of the station, suspended on its two sides by chains driven by only one motor through a transmission shaft.
The elevating device preferably includes correction means and means for the maintenance of the horizontality of the upper side of the bars forming the non-stop delivery rack. These correction means can include lateral racks and guidance rollers and/or torsion bars connecting distant parts of the vertically movable frame.
The vertical run of the non-stop delivery rack can be adjustable between a high position, where the waste height is preferably minimal, and a low position, this low position being determined by the length of the lower blanking tool joggers.
This low position can be preset: the length of the low blanking tool joggers is usually known and can thus be stored while programming the machine. Instead of including this parameter into the program, one can also detect the position of the rack compared to the joggers. To do so, the vertically movable frame can carry, upstream of the transverse roller, a feeler arm horizontally scanning the space located immediately below the free ends of the bars forming the delivery rack, so as to detect the height of the frame where the rack goes down below the lower end of the joggers.